Field of the Invention
The present invention relates to a magnetism suppressing sheet that suppresses radiation of electromagnetic wave noise from a noise source and a manufacturing method thereof.
Description of Related Art
In recent years, a mobile electronic apparatus such as a smart phone is strongly required to take countermeasures against noise. As one of the noise suppression methods, there is a method that covers a noise source with a magnetism suppressing sheet so as to protect an internal circuit from external noise and prevent unnecessary radiation of noise generated in the apparatus. For example, Japanese Patent Application Laid-Open No. H07-212079 discloses, in FIG. 4, an electromagnetic wave interference suppressor that includes a conductive support and an insulating soft magnetic material layer provided at least on one surface of the conductive support, wherein the conductive support is formed of a metal plate. Further, Japanese Patent Application Laid-Open No. H09-312489 discloses, in FIG. 4, a countermeasure against EMI using an electromagnetic interference suppressor including a composite magnetic body constituted of soft magnetic powder and an organic binder and a conductive layer formed, by plating, on an outside surface of the composite magnetic body.
However, the electromagnetic wave interference suppressor disclosed in Japanese Patent Application Laid-Open No. H07-212079 uses a metal plate as the conductive support, so that reduction in thickness of the conductive support is difficult. Further, in the electromagnetic interference suppressor disclosed in Japanese Patent Application Laid-Open No. H09-312489, the conductive layer is formed, by plating, on the surface of the composite magnetic body, so that formation of a thin and uniform (in thickness) plating film is difficult.